The present invention relates to an evaluation device and an evaluation method for performing a collective reliability evaluation with respect to a plurality of reliability evaluation elements formed on a semiconductor wafer.
In recent years, a semiconductor element is expected to respond to such requirements as a continuous operation for a long period of time and a stable operation at a high temperature, in which the reliability evaluation for the semiconductor element is indispensable. Further, it is requested that the reliability evaluation be performed in a wafer state in order to improve the productivity and the reliability evaluation be collectively performed in the wafer state in accordance with an increasingly enlarging diameter of the wafer. As another point to be noted, operation conditions required for the semiconductor element are becoming more demanding, in response to which there is an increasingly higher expectation for performing the evaluation at a higher temperature and under more precise temperature conditions.
Hereinafter, reliability evaluation devices, which are conventionally used in the wafer state, are described referring to FIGS. 13 and 14.
(First Example of Conventional Art)
FIG. 13 is a schematic illustration of an evaluation pattern of a reliability evaluation device for performing the reliability evaluation in the wafer state according to a first conventional example (see Japanese Unexamined Patent Publication No. 06-151537 of the of the).
In FIG. 13, a heating element 101 using a conductive layer selectively formed by means of, for example, ion implantation is formed on a semiconductor wafer, and a reliability evaluation pattern 103 is formed on the heating element 101 via an insulation film (not shown). The reliability evaluation pattern 103 is connected to electrodes 104a, 104b, 104c and 104d. The heating element 101 is connected to ohmic electrodes 102a and 102b. A probe terminal of a prober is brought into contact with the electrodes 104a, 104b, 104c and 104d to thereby apply voltage or current to the evaluation pattern 103 so as to perform the reliability evaluation. At that time, current is applied to the heating element 101 via the ohmic electrodes 102a and 102b to thereby generate heat from the heating element 101 so as to control a temperature of the evaluation pattern 103.
The foregoing configuration has advantages that the temperature of the evaluation pattern can be precisely controlled and a heat balance can be reached in a short period of time because the heating element is disposed immediately below the evaluation pattern.
(Second Example of Conventional Art)
FIG. 14 is a schematic illustration of a reliability evaluation device using a wafer collective probe capable of collectively performing an inspection and reliability evaluation with respect to an entire surface of the wafer according to a second conventional example (see No. 2828410 of the Publication of the Patented Patents).
Referring to reference numerals in FIG. 14, 111 denotes a semiconductor wafer, 112 denotes a wafer collective probe and 113 denotes a wafer tray. Electrodes 111a and reliability evaluation elements 111b are formed on the semiconductor wafer 111. The electrodes 111a and the reliability evaluation elements 111b are electrically connected.
As shown in FIG. 14, the wafer collective probe 112 comprises a wiring substrate 112a, an anisotropic conductive rubber 112b and bumps 112c. The bumps 112c are provided in positions in the wafer collective probe 112 corresponding to the electrodes 111a on the semiconductor wafer 111. The wiring substrate 112 and the bumps 112c are electrically connected by means of the anisotropic conductive rubber 112b. 
In the state shown in FIG. 14, the electrodes 111a on the semiconductor wafer 111 and the bumps 112c on the wafer collective probe 112 are electrically connected. Thereafter, voltage or current is applied to the respective reliability evaluation elements 111b on the semiconductor wafer 111 to thereby perform the reliability evaluation. Further, a heater is directly brought into contact with the wafer tray retaining the semiconductor wafer so as to uniformly control a temperature of the entire surface of the semiconductor wafer 111.
According to the foregoing configuration, the wafer can be collectively evaluated, which includes such an advantage as a large reduction of evaluation time.
According to the configuration according to the first conventional example, however, only a few or so can be evaluated at a time because the probe terminal of the prober is used. The first conventional example thus includes a problem that an enormous amount of time is consumed for evaluating the entire surface of the wafer or a variation in the wafer surface due to the fact that the reliability evaluation generally requires tens of hours or more in one evaluation.
According to the second conventional example, the anisotropic conductive rubber 112b constituting the wafer collective probe has a low heat resistance. For example, when the evaluation is continued at, for example, 150° C. or more, the anisotropic conductive rubber 112b is apparently deteriorated, which largely increases a conductive resistance thereof. This creates a problem that the reliability evaluation can only be performed in a narrow temperature range.
The second conventional example includes further problems that a variation is generated in actual evaluation temperatures of the respective reliability evaluation elements because the reliability evaluation elements are collectively heated by the heater, which is brought into contact with the wafer tray, and further, the actual evaluation temperature of each reliability evaluation element cannot be precisely known.